Polymerization of alpha-acyloxyacrylonitriles in aqueous systems using a redox catalyst and polymers obtained therefrom



pure mm and in the Patented Sept. 15, 1953 POLYMERIZATION' F NITRILES IN AQUEO A REDOX CATALYST a-ACYLOXYACRYLD- US SYSTEMS USING AND POLYMERS 0B- ramnn THEREFROM Hugh J. Hagemeyer, Jr., K n port, Tenn, as-

signor to Eastman Kodak oamp y, Rochestr,

N. Y., a. corporation of Netrlrsey No Drawing. Application August 1 8', 1950, Serial N0. 180,297

12. Claims. (Cl. 260 -80-5 This invention relates to a new method for polymerizing a-acyloxyacryloni-triles, and more particularly u-acetOXyacryIOnitriIe, in aqueous systems.

The polymerization of e-acyloxyacrylonitriles, such as a-acetoxyacryloni'trile, alone or in the presence of other ethenoid monomers has been mentioned previously, although no methods whereby such polymerization could be effected have been described. (U. S. Patent 2,395,930, dated March 5, 1947 and U. S. Patent 2,266,771, dated December 25, 1 941). In U. S. Application Serial No. 777,376, filed October 1, 194?,nowU. 3. Patent 2,537,881, issued January 9, 1951, of Joseph B. Dickey a method v tion of interpolymerization of a-acyloxyacrylonitrilesis described, although mention is madeoi' simple emulsion polymerizations. The polymers obtained by the mass method are of little utility in the form obtained and must be purified by extraction and. like before obtaining a "tinished product, although such "mass polymers can be used without treatment for the esterification methods described in Serial No. 777,376. Ordinary emulsion polymerization of a-acyloxyacryl'onitriles, such as e-acetoxyacrylonitrile, is not practicablasince the rate of hydrolysis oi the ester-nitrile exceeds its rate of polymerization under such conditions (see, for example, .Deakin et al'. Jour. Chem. Soc. (Londonl910),'vol. 97. 91).1968-1978), and yields of polymer are low.

The present invention provides a: method for obtaining polymers of a-aicyloxyacrylon-itriles in substantial absence of hydrolysis products.

objector my invention is'toprouide an improved method for preparing polymers of aiacyloxyacrylon itrilesi A further object is to provide an improved method for polymerizing acetoxyacrylonitrile' alone, or in the presence of another ethenoid monomer. "still another object is to provide new interpolymers of @QOYIGXY- acrylonitriles. Other objects will become up parent from a consideration ofthefollowing descriptionand examplea l 1 According to my invention 1 polymerize a acyloiryacrylonitnileswalone, or in thepresence :of another ethenoid monomer, in an aqueous dispersion in the presence of ca persulfateipolymerization catalyst and a water-soluble, oxidizable compoundcfsulfur. V

The aeacyloxyacrylonitriles which .I use in practicing my invention can advantageously be represented by the following general formula:

capo-can wherein represents .alkyligroup, such as methyl; ethyl, .n-'-prcpy1, iscpropyl; 'e'tc. groups of mass polymer iza- (e. g. alkyl group of the formula Gilliam wherein n represents a positive integer of mm -1 to 3). Typical e acyloxyacrylonitriles include a-acetoxyacrylonitrile, a-propionoxyacrylonitrile, a n butyroicyaoryloriitiile, aisobutyroxyaci'ylonitrile, etc.

'The polymerization of one or more of the dacyloxyacrylonitriles is eii'ected according to my invention in an aqueous dispersion (i. e. solution, emulsion, or granular polymerization). Surficient watercan be'used to dissolve the monomers, or if desired, the amount of waterused can be adjusted to the extent that no water in excess of that required for complete solution is present. A dispersing agent can be added to produce a stable emulsion, or a granulating agent can be added, if desired, and the polymerization then effected. Typical emulsifying or dispersing agents include, for example, alkali metal dialkyl sulfosucc'inates (e. g. sodium di-2-ethylhexylsulfosuccinate, sodium di-n-butylsulfosuccinate, sodium :dioctyl sulfosuccinate, etc),- alkali metal alkyl-naphthalenesulfonates (e. g. sodium isopropylnaphthalenesulionate, sodium isobutylnaphthol'enesulionate, etc), alkali metalsalts of long-chain alkyl sulfates Ce. g. sodium lauryl sulfate, potassium stearyl sulfate, etc.)., alkali metal salts of parafiin oil sulfonic acids (e. g. sodium para-11in oil sulfonate, etc), alkali metal salts of long-chain aikylsulfonates (e. g. sodium laurylsulfonate, potassium steaiylsulfonate, etc), etc. Typical granulating agents include ,polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, alkali metal polyacrylates and polyznethacrylates (e. g. sodium polyacrylate; etc). starch others (e. g. methylated starch), methyl cellulose, polyacrylamides, etc. The amount of emulsifying or granulating agent "used can be varied, however, I have found that from about 0.11:0 1.0 per cent of such agents, based on the total weight of the monomers being polymerized; is sufiicient, although up to about 5. 0 per cent of such agents can be used; depending upon the dispersing power of the particular dispersing a ent;

Persulfate polymerization catalysts which can vantageously :be employed in practicing my inlithium, etc:persulfatesi Water-soluble, oxidizable compounds of sulmr which can be used practicing my invention comprise e wellelmown reducing agents of sulfur (1.: e; compounds of sulfur having a valence of 2"or 4 Typical water-soluble, :oxidizahle sulfur include, for example, the alkali metal" bisulfltes (e. g. sodium, potassium, etc. bisulfites), ammonium bisulfite, alkali metal and ammonium sulfites (e. g. sodium; potassium, ammonium, etc. sulfltes), alkali metl and ammonium thiosulfates (e. g. sodium, potassium, ammonium, etc. thiosulfates), alkali metal sulfides (e. g. sodium potassium, etc. sulfides), ammonium sulfides (e. g. ammonium sulfide, ammonium polysulfides, etc.), alkali metal hydrosulfides (e. g. sodium, potassium, etc. hydrosulfides), ammonium hydrosulfide, hydrogen sulfide, sulfur dioxide, organic sulfinic acids (e. g. p-toluenesulfinic acid, benzenesulfinic acid, xylenesulfinic acids le. g. o-xylene-3-sulfinic acid, o-xylene- 4-sulf1nic acid, etc], methanesulfinic acid, ethanesulfinic acid, ethanedisulfinic acid, etc.), or alkali metal salts of these sulfinic acids where the particular acid does not have sufiicient solubility in water at the polymerization temperature, diethyl sulfite, diethylsulfoxide, etc. The term alkali metal as used herein is intended to define the metals of group I of the periodic table of the elements.

The persulfate polymerization catalyst is activated by the water-soluble compound of sulfur, which lowers the induction period proceeding the initiation of the polymerization. In the absence of these activators, little polymerization can be detected and the a-acyloxyacrylonitriles undergo extensive hydrolysis. Moreover, the organic acid liberated during hydrolysis inhibits the polymerization.

The activators are also useful in providing a convenient method for regulating the molecular weight of the polymers, the molecular weight being a function of the quantity of activator employed.

The quantity of persulfate catalyst can be varied, depending on the conditions of polymerization and the quantity of material being polymerized. Generally, I have found that from 0.1 to 4 per cent by weight, basedon the materials being polymerized, is sufficient for the purposes of my invention. Especially useful polymers have been obtained when from about 1 to 2 per cent by weight of persulfate was employed. The quantity of water-soluble compound of sulfur used as an activator can be varied, and is generally a function of the materials being polymerized, temperature of polymerization, etc. Generally, from 0.5 to '7 molar equivalents of the activator for each molar equivalent of persulfate catalyst, are adequate for practicing the process of my invention. A more limited range which can be usedis from 2 to 4 molar equivalents of the activator for each molar equivalent of the persulfate polymerization catalyst, especially where from 1 to 2 per cent by weight, based on the total weight of polymerizable materials present, of persulfate polymerization. catalyst is used. Larger or smaller amounts of the activator can be used, if desired, although there is ordinarily no advantage in doing so. About -5 molar equivalents of activator for each equivalent of persulfate has been found to give especially useful results.

Heat accelerates the polymerization and temperatures varying from about to 90 C. have been found to be useful. Temperatures as low as about 0 C. can be used, as shown in the examples below.

While the process of my invention is especially useful for the homopolymerization of a-acryloxyacrylonitriles, it can also be used advantageously for the interpolymerization of a-acyloxyacrylonitriles with one or more compounds containing ethenoid unsaturation, i. e. compounds containing an acyclic -CH=C group, such as, for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, .vinylbenzoate, divinyl phthalacrylate, n-propyl acrylate, isopropyl acrylate, n-

butyl acrylate, isobutyl acrylate, secondary butyl acrylate, methyl a-methacrylate, ethyl a-methacrylate, propyl a-methacrylate, isopropyl a.- methacrylate, n-butyl a-methacrylate, isobutyl a-methacrylate, secondary butyl a-methacrylate, benzyl acrylate, benzyl amethacrylate, vinyl chloride, vinylidene chloride, styrene, a-methylstyrene, a-acetoxystyrene, a-chlorostyrene, pacetaminostyrene,- p-sulfamylstyrene, isopropenyl acetate, isopropenyl propionate, methyl a-ChlOIO- acrylate, ethyl a-chloroacrylate, n-propyl a-ChlO- roacrylate, acrylamide, N-methyl acrylamide, N- ethyl acrylamide, N,N'-diethyl acrylamide, amethacrylamide, acrylonitrile, a-methacrylonitrile, dimethyl fumarate, diethyl fumarate, di-npropyl fumarate, diisopropyl fumarate, di-nbutyl fumarate, dimethyl maleate, diethyl maleate, di-n-propyl maleate, diisopropyl maleate, din-butyl maleate, dibenzyl fumarate, dibenzyl maleate, diallyl fumarate, dimethallyl fumarate, diallyl maleate, dimethallyl maleate, methyl vinyl ketone, ethyl vinyl ketone, n-propyl vinyl ketone, n-butyl vinyl ketone, methyl isopropenyl ketone, ethyl isopropenyl ketone, divinyl ketone, diisoprop-enyl ketone, fl-chloroallyl acetate, methyl 0.- chloroacrylate, s-chloro-aemethallyl acetate, maleic anhydride, a-chloroacrylonitrile, vinyl sulfonamide, a-methyl vinyl sulfonamide, maleic imide, N-butyl maleic imide, a-chloroacrylic acid, acrylic acid, a-methacrylic acid, maleic acid, fumaric acid, fumaronitrile, maleic nitrile, itaconic acid, citraconic acid, methyl itaconate, ethyl itaconate, and the like.

Following the polymerization, the polymer products are washed well with water and then dried. Interpolymers of the e-acyloxyacrylonitriles and acrylonitrile containing from 50 to per cent molecule give clear, viscous solutions in solvents for polyacrylonitrile, such as N,N-dimethylformamide, N,N-dimethylacetamide, v-butyrolactone, ethylene carbamate, ethylene carbonate, N- methyl-Z-pyrrolidone, etc. These viscous solutions containing from 10 to 30 .per cent by weight of polymer can be extruded through an orifice into a coagulating bath containin a liquid, such as water, alcohols, etc. whichis a non-solvent for the polymer. The resulting filaments can be stretched or drafted from to 1400 per cent, dried, relaxed, and twisted to give yarns characterized by good strength, elasticity, and dyeing properties.

Ternary interpolymers comprising an a.- acyloxyacrylonitrile (e. g. racetoxyacrylonitrile), acrylonitrile, and isopropenyl acetate have been found to be especially useful as raw materials for the preparation of fibers and yarns, films, tapes, etc. Interpolymers-containing from 5 to 90 per cent by weight of the a-acyloxyacrylonitrile, 5 to 90 per cent by weight of acrylonitrile, and 5' to 30 per cent by weight of isopropenyl acetate are particularly suitable for such purposes.

The following examples will serve to illustrate more fully the manner whereby I practice my invention.

' Example 1.--Homopolym'erizaticn of a-acetoxyacrylonitrile 350 cc. of distilled water having dissolved therein 1.0 g. of ammonium persulfate and 2.0 g. of sodium bisulfite were stirred while 10.0 gpof sodium dioctylsulfosuccinate were added. The

by weight of acrylonitrile in the polymer Example 3.l1iter.polymer I -solution was then stirred at2-6 C. while 65 g. oi a acetoxyacrylonitnle :(B. P. 61 (31/10 :mm., N 1.4260) were run in over a period, of two hours, at the end of which time a white emulsion had formed. After allowing the reaction mixture to stand for two hours, it was poured into one liter of .25 per cent aqueous ethanol and allowed to stand overnight. The emulsionbecame thick and creamy, the suspended polymer was coagulated by adding 5g. of sodium chloride, two drops of sulfuric :acid, and heating with 'stirring. The solid phase became yellow "and the water phaseorange. The polymer was collected on a Buchner funnel, washed with water, and air and ovemdri'ed to give 45 g. (69 percent) of tan "soiid. l 1 Example z.--Homopolvmerization 07' a-acetoryacrylonitrile This example wasperformed in the samemannor as Example 1, except that polymerization was effected at and no emulsifying agent was employed. Thesolution, after polymerization for three hours was poured into 300 cc. of

"dilute sodium chloride -sol-i1 tion, but the ooagulum 0 would not be filtered. The coagulum was then heated on a steam -ba'th for two hours, and the cream coiored coagulate d. It wasflltc'red on a Buclmer tunnel and washed three times with water. There were thus obtained 'g. (47 percent) of drypolymer consisting of tan powder and lumps. It was soluble in N,N-dimethylformamide. l

tr'z'le and acrylonitr'ile In a three-liter flask were placed 1400 cc. of distilled water, which was heated to .35" C. be- Ji'ore adding 1.0 g. of ammonium persulfate,, 1.0

g. of sodium bisulfite, 96 g. of freshly distilled acrylonitrile (N 1.3920), and 4.0 g. of redistilled a-acetoxyacrylonitrile. The flask was then purged with nitrogen gas, and the contents stirred for six hours while the temperature was maintained at C. During the .first hour it-was necessary to cool externally. The white polymer slurry, which formed was filtered, and washed with water. After drying, the white .powder 13.52 grams .per 'tion when wet. Example 4.-'Interpolymer of a-acetomyacflilonitr'ile, 'isoprop'e'nyl :acetate, nd ocrylonltrile In the same manner as described in 3 above, 1400- cc. of water, 120 g. of persulfate, 1.0 :g. of sodium bisul'fite, 90 g. of .acrylonitri-le, 5:0 g. of isopropenyl acetate, and 5.0 g. a-acetoxyacryl'onitrile were added to a threeliter .flask. The polymerization was effected at a temperature of from "40 C. to 44 C. over a. period "oftwenty hours. white slurry was then 'coa'gulated by adding liter-of watercoutaining :g. "of aluminum sulfate and about 250 cc.-of acetone. After collecting the polymer on a Buchner funnel. it was washed "well with water and dried. It. weighed *97 .g. Q I per cent) and gave a viscous solution in N,N-dimethylf0mna.mide having a relative viscosity of 1.489. A multifilament yarn spun by extruding the solution into an isopropanol bath, followed by drafting of the filaments in hot air, had a. strength of 2.58 grams per denier and :an elongation of 23 per cent. ,When wet, the yarn had a strength 0112.26 grams per denier and an elongation of 28 .per cent.

. I In like manner, 80.0 g. of acrylonitrile, 10:0 4;. of isopropenyl acetate and 10.0 g. of a-aoetoxy- .acrylonitrile were polymerized together. An 84 per cent yield of polymer was obtained after 24 hours at 35-38 C. Yarns spun by extruding a solution-of the polymer in mN-di-methyliormamide into a precipitating bath had an excellent-aifinity for cellulose acetate dyes.

In the manner described in Example 3 above, acrylonitrile and u-acetoxyacrylonitrile were interpolymerized in the amounts given in the table below. The reaction mixtures were heated for the times and at the temperatures indicated. .and the polymers were washed and dried as described in Example 3. The yields of polymers are set .forth in the table. Each of the polymer products was then dissolved in separate portions denier and .o. 20 per cent elonga- 10f N,N-dimethyltormamide, and the resulting solutions spun into coagulating baths. The .properties of the fibers formed are summarized below.

AAN=a-Acetoxyacrylonltrile.

g./d.- Grams per denier.

E Elonganon.

-=Ihe temperature on th before processing.

weighed 94 g. (94 per cent), and it was soluble in- N,N-dimethylacetamide. It gave a viscous solution in N,N-dimethylformamide having a relative viscosity of 1.48. Fibers spun from this solution had a strength of 3.34 grams per denier, 20 per cent elongation at break, a wet strength of is sample was allowed to drop trom 44 C. to 26 C. over a period or 16.5 hrs.

By replacing the a-acetoxyacrylonitrile used in the above examples by a molecularly equivalent amount of other a-acyloxyacrylonitriles, e. g. upropionoxyacrylonitrile, c-isobutyroxyacrylonitrile, a-ll-blltYIOXYflOIYlOl-fltlflfi, etc., other useful polymers can be obtained.

The. water-soluble;oxidizable compounds of sulfur, which must be employedicfor successful operation of my invention, are well recognized in the art as reducing agents, the valence of the sulfur being either 2 'or 4. In the preparation of interpolymers I have found that, in general, it is advantageous to have the monomeric mixture contain from 5 to 95 per cent by weight of the a acyloxyacrylonitrile, the remainder being another polymerizable compound, although these amounts can be varied according to the proposed "use to which the polymer is to be adapted.

What I claim as my invention and desire secured by'Letters Patent of the United States is:

1. A process for preparing polymers of a-acyloxyacrylonitriles in the substantial absence of hydrolysis thereof comprising polymerizing an a-'acyloxyacrylonitrile represented by the following general formula:

' CH2=C-OEN -mula -CnHzn+1 wherein n represents a positive integero'f from 1 to 3, in an aqueous dispersion in the! presence of a persulfate polymerization catalyst and a water-soluble, alkaline bisulfite. 3. A process: for preparing polymers of a acyloxyacrylonitriles in the substantial absence of hydrolysis thereof comprising polymerizing an a-acyloxyacrylonitrile represented by the following general formula: i CHa=C-OEN mula CnI-IZn wherein n represents a positive integer of from 1 to 3, in an aqueous dispersion 5. A process for preparing polymers of facetoxyacrylonitrile .in the substantial absence of hydrolysis thereof comprising polymerizing (ii-acetoxyacrylonitrile in an aqueous dispersion in the presence of a persulfate polymerization catalyst and sodium bisulfite.

6. A process for preparing polymers of a-acetoxyacrylonitrile in the substantial absence of hydrolysis thereof comprising polymerizing a-acetoxyacrylonitrile in an aqueous dispersion in the presence of a persulfate polymerization catalyst and potassium bisulfite.

7. A process forpreparing polymers of a-acetoxyacrylonitrile in the substantial absence of hydrolysis thereof comprising polymerizing a-acetoxyacrylonitrile in an aqueous dispersion in the presence of a persulfate polymerization catalyst and sodium thiosulfate.

8. A process for preparing polymers of a-acetoxyacrylonitrile in the substantial absence of hydrolysis thereof comprising polymerizing a-acetoxyacrylonitrile in an aqueous dispersion in the wherein Rrepresents an alkyl group of the forin the presence of a persulfate polymerization catalyst and-a water-soluble, alkaline thiosulfate.

4. A process for preparing polymers of Iii-aceti oxyacrylonitrile in the substantial absence of hydrolysis thereof comprising polymerizing a-acetoxyacrylonitrile in an aqueous dispersion in the j presence of a persulfate polymerization catalyst,

and a water-soluble, oxidizable compound of sulfur.

presence of ammonium persulfate and sodium bisulfite.

9. A process for preparing polymers of a-acetoxyacrylonitrile in the substantial absence of hydrolysis thereof comprising polymerizing u.- acetoxyacrylonitrile in an aqueous dispersion in the presence of ammonium persulfate and potassium bisulfite.

10. Aprocess for preparing polymers of aacetoxyacrylonitrile in the substantial absence of hydrolysis thereof comprising polymerizing a.- acetoxyacrylonitrile an aqueous dispersion in the presence of ammonium p ersulfate and sodium thiosulfate.

11. Aternary interpolymer containing from 5 to .per cent by weight of an a-acyloxyacrylonitrile represented by the following general formula:

CHFC CEN CR wherein R. represents an alkyl group of the formulaCnH21r+1 wherein n represents a positive integer of from 1 to 3, 5 to 90 per cent by weight of acrylonitrile and from 5 .to 30 .per. cent by weight of isopropenyl acetate.

12. A'ternary interpolymer containing from 5 to 90 per cent by Weight of e-acetoxyacrylonitrile,

5 to 90 per cent by weight of acrylonitrile, and from 5 to '30 per cent by weight of isopropenyl acetate.

I HUGH J. HAGEMEYER, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,395,930 Johnston et a1 Mar. 5, 1946 2,453,824 Wood Nov. 16, 1948 2,462,354 Brubaker Feb. 22, 1949 2,475,423 1 v, Dickey July 5, 1949 2,537,881 Dickey Jan. 9, 1951 

1. A PROCESS FOR PREPARING POLYMERS OF A-ACYLOXYACRYLONITRILES IN THE SUBSTANTIAL ABSENCE OF HYDROLYSIS THEREOF COMPRISING POLYMERIZING AN A-ACYLOXYACRYLONITRILE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 